Can I take legal action against the CSA?

I first applied to the csa in september 2009 in december 2009 i hadnts heard anything so i phoned them I was told that my claim had been cancelled of the computer system and i would have to reapply which i did, i was then told it would have to be done clericly as the computer system would not let them put my case back on. it was continuas phone calls every month to keep a track on things but they where not very forthcomeing with any information.

I then received a cheque in august 2010 for £50 I was told this was compensation for the time i had waited, I never cashed the cheque which I still have as I think this is an insult to me and my children as this has put so much pressure on all of us, in september 2010 on the 8th day I finaly got a letter of them saying how much he had to pay when I read the letter I noticed that there was 4 children on the case I phoned the csa as I have 3 children with him and he has 1 child with his new wife.

I was told that they could not give me any information other than his wife had put a claim in for her daughter I told them they had not split up and they said all the information she had given checked out and they could not do anything about it, it also took till november to get any payments.

I eventually called the benefits fraud line and asked them to look into it further, I received a phonecall in december 2010 a few days before new years eve and was told than there was a change in circumstances and that my money would be going up. but still I was haveing touble getting my money every month I was haveing to wait a full month before I received the money, and have had to continuasley phone them on the 28 feb this year I received a letter saying my payments would be going up from april which is absolutley rediculouse it is not 12 march and still not received the money he paid last month on the 16 I have had to phone every day to find out where the payment is and this is what it is like every month you get passed from pillar to post in the call centre. Some of the people you speak to are even nasty with you they never want to put you through to a manager or supervisor and when you do they tell you they have no authority so why have them this is an absolute discrace to single mums when all we want is what is right for our children. Can I sue them?